This section provides background information related to the present disclosure which is not necessarily prior art.
Strut-type suspension systems are well known in the motor vehicle industry. A telescopic strut assembly normally incorporating a hydraulic damper is used as one of the locating members for the wheel of the motor vehicle. The most common form of a strut-type suspension is the McPherson strut suspension system. The McPherson strut assembly includes a coil spring located concentrically around the telescopic strut which is the shock absorber. The upper end of the McPherson strut assembly includes an upper mounting assembly which is mounted in a tower formed by the vehicle body at a position above the wheel arch of the vehicle.
The coil spring is located around the shock absorber and it extends between an upper spring seat which is a part of the top mount assembly for the strut assembly and a lower spring seat which is attached, typically by welding, to the shock absorber of the strut assembly. The spring seats of the strut assembly have several functions for the suspension system. The spring seats support and maintain the correct position of the spring and support the loading on the spring under all driving conditions of the vehicle for the entire life of the vehicle. The spring seats are mechanically resistant during the life of the vehicle. They resist braking loads, deformations, wear, abrasion, changing loads and hits by stones and other debris. The spring seat is environmental and corrosion resistant to different temperatures, different moisture levels, aggressive liquids and gasses. The spring seats ensure proper fixing of the components of the strut assembly, easy assembly of the strut assembly into the vehicle and with the other components of the strut assembly they resist any unwanted displacements and/or rotations. The design of the spring seats also ensure that the spring to spring seat contact does not promote or accelerate corrosion of the spring or the spring seat.
The prior art low spring seats are typically a single piece stamped or formed component. The single piece lower spring seat includes an annular disc that supports the lower end of the spring and a tubular extension which extends from the annular disc. The tubular extension is designed to be welded or otherwise attached to the outer tube of a hydraulic damper or shock absorber that is a component of the telescopic strut assembly.
The tubular extension defines a center axis which is located at an angle with respect to the planar surface defined by the annular disc that supports the lower end of the spring. The center axis of the tubular extension is co-linear with a center axis defined by the outer tube of the hydraulic damper or shock absorber. The angle between the center axis of the tubular extension and the planar surface defined by the annular disc is determined by the design specifications for the suspension assembly and thus each lower spring seat can have a different angular relationship.
This difference in angular relationship can create issues when designing the assembly equipment for the telescopic strut assembly. Typically, the tubular extension of the lower spring seat is press fit over the outer tube of the hydraulic damper or shock absorber. Because the wall thickness of the tubular extension is too thin to act as a bearing surface for the tooling during the press fit operation, the tooling that presses the lower spring seat onto the outer tube of the hydraulic damper or shock absorber must be designed to bear against the annular disc of the lower spring seat. Thus, for each design of lower spring seat, a new set of press fit tooling needs to be designed and manufactured.